Topographic disequilibrium, landscape dynamics and active tectonics: an example from the Bhutan Himalayas

2021 ◽  
Author(s):  
Martine Simoes ◽  
Timothée Sassolas-Serrayet ◽  
Rodolphe Cattin ◽  
Romain Le Roux-Mallouf ◽  
Matthieu Ferry ◽  
...  
Keyword(s):  
Spatial Organization ◽  
Spatial Scales ◽  
Active Tectonics ◽  
Recent Change ◽  
Climatic Conditions ◽  
Landscape Dynamics ◽  
Drainage Basins ◽  
Equilibrium Conditions ◽  
Longitudinal Band ◽  
Active Tectonic

<p>The quantification of active tectonics from geomorphological and morphometric approaches most often implies that erosion and tectonics have reached a certain balance. Such equilibrium conditions may however be seldom found in nature, in particular because drainage basins may be quite dynamic even though tectonic and climatic conditions remain constant. Here, we document this drainage dynamics from the particular case example of the Bhutan Himalayas. Evidence for out-of-equilibrium morphologies have for long been noticed in Bhutan, from major (> 1 km high) river knickpoints and from the existence of high-altitude low-relief regions within the mountain hinterland. These peculiar morphologies were generally interpreted as representing a recent change in climatic and/or tectonic conditions. To further characterize these morphologies and their dynamics, and from there discuss their origin and meaning, we perform field observations and a detailed quantitative morphometric analysis using Chi plots and Gilbert metrics of drainages over various spatial scales, from major Himalayan rivers to local streams draining the low-relief regions. We first find that the river network is highly dynamic and unstable. Our results emphasize that the morphology of Bhutan does not result from a general wave of incision propagating upstream, as expected from most previous interpretations. Also, the specific spatial organization in which all major knickpoints and low-relief regions are located along a longitudinal band in the Bhutan hinterland, whatever their spatial scale and the dimensions of the associated drainage basins, calls for a common local supporting mechanism most probably related to active tectonic uplift. Our results emphasize the need for a precise documentation of landscape dynamics and disequilibrium over various spatial scales as a first-order step in morpho-tectonic studies of active landscapes.</p>

scholarly journals Topographic disequilibrium, landscape dynamics and active tectonics: an example from the Bhutan Himalayas

2020 ◽  
Author(s):  
Martine Simoes ◽  
Timothée Sassolas-Serrayet ◽  
Rodolphe Cattin ◽  
Romain Le Roux-Mallouf ◽  
Matthieu Ferry ◽  
...  
Keyword(s):  
Spatial Organization ◽  
Spatial Scales ◽  
Active Tectonics ◽  
Recent Change ◽  
Climatic Conditions ◽  
Landscape Dynamics ◽  
Drainage Basins ◽  
Equilibrium Conditions ◽  
Longitudinal Band ◽  
Active Tectonic

Abstract. The quantification of active tectonics from geomorphological and morphometric approaches most often implies that erosion and tectonics have reached a certain balance. Such equilibrium conditions may however be seldom found in nature, as questioned and documented by recent theoretical studies, in particular because drainage basins may be quite dynamic even though tectonic and climatic conditions remain constant. Here, we document this drainage dynamics from the particular case example of the Bhutan Himalayas. Evidence for out-of-equilibrium morphologies have for long been noticed in Bhutan, from major (> 1 km high) river knickpoints and from the existence of high-altitude low-relief regions within the mountain hinterland. These peculiar morphologies were generally interpreted as representing a recent change in climatic and/or tectonic conditions. To further characterize these morphologies and their dynamics, and from there discuss their origin and meaning, we perform field observations and a detailed quantitative morphometric analysis using Chi plots and Gilbert metrics of drainages over various spatial scales, from major Himalayan rivers to local streams draining the low-relief regions. We first find that the river network is highly dynamic and unstable. Our results emphasize that the morphology of Bhutan does not result from a general wave of incision propagating upstream, as expected from most previous interpretations. Also, the specific spatial organization in which all major knickpoints and low-relief regions are located along a longitudinal band in the Bhutan hinterland, whatever their spatial scale and the dimensions of the associated drainage basins, calls for a common local supporting mechanism most probably related to active tectonic uplift. From there, we discuss previous interpretations of the observed landscape in Bhutan. Our results emphasize the need for a precise documentation of landscape dynamics and disequilibrium over various spatial scales as a first-order step in morpho-tectonic studies of active landscapes.

scholarly journals Topographic disequilibrium, landscape dynamics and active tectonics: an example from the Bhutan Himalaya

2021 ◽  
Vol 9 (4) ◽  
pp. 895-921
Author(s):  
Martine Simoes ◽  
Timothée Sassolas-Serrayet ◽  
Rodolphe Cattin ◽  
Romain Le Roux-Mallouf ◽  
Matthieu Ferry ◽  
...  
Keyword(s):  
Spatial Organization ◽  
Spatial Scales ◽  
Active Tectonics ◽  
Climatic Conditions ◽  
Landscape Dynamics ◽  
Drainage Basins ◽  
Equilibrium Conditions ◽  
Longitudinal Band ◽  
Active Tectonic ◽  
Landscape Response

Abstract. The quantification of active tectonics from geomorphological and morphometric approaches commonly implies that erosion and tectonics have reached a certain balance. Such equilibrium conditions are however rare in nature, as questioned and documented by recent theoretical studies indicating that drainage basins may be perpetually re-arranging even though tectonic and climatic conditions remain constant. Here, we document these drainage dynamics in the Bhutan Himalaya, where evidence for out-of-equilibrium morphologies have for long been noticed, from major (> 1 km high) river knickpoints and from high-altitude low-relief regions in the mountain hinterland. To further characterize these morphologies and their dynamics, we perform field observations and a detailed quantitative morphometric analysis using χ plots and Gilbert metrics of drainages over various spatial scales, from major Himalayan rivers to their tributaries draining the low-relief regions. We first find that the river network is highly dynamic and unstable, with much evidence of divide migration and river captures. The landscape response to these dynamics is relatively rapid. Our results do not support the idea of a general wave of incision propagating upstream, as expected from most previous interpretations. Also, the specific spatial organization in which all major knickpoints and low-relief regions are located along a longitudinal band in the Bhutan hinterland, whatever their spatial scale and the dimensions of the associated drainage basins, calls for a common local supporting mechanism most probably related to active tectonic uplift. From there, we discuss possible interpretations of the observed landscape in Bhutan. Our results emphasize the need for a precise documentation of landscape dynamics and disequilibrium over various spatial scales as a first step in morpho-tectonic studies of active landscapes.

Quantifying active tectonics in the case of dynamic and instable landscape: an example from the Bhutan Himalayas

2020 ◽  
Author(s):  
Timothee Sassolas-Serrayet ◽  
Martine Simoes ◽  
Rodolphe Cattin ◽  
Romain Le Roux-Mallouf ◽  
Matthieu Ferry ◽  
...  
Keyword(s):  
Spatial Scales ◽  
Active Tectonics ◽  
Recent Change ◽  
Climatic Conditions ◽  
Mountain Range ◽  
Theoretical Studies ◽  
Drainage Basins ◽  
Equilibrium Conditions ◽  
Regional Tectonic ◽  
Climatic Evolution

<p>The quantification of active tectonics from geomorphological and morphometric approaches most often implies that erosion and tectonics have reached a certain balance. Such equilibrium conditions may however be seldom found in nature, as questioned and documented by recent theoretical studies, in particular because drainage basins may be quite dynamic even though tectonic and climatic conditions remain constant.</p><p>Here, we document this drainage dynamics from the particular case example of the Bhutan Himalayas. Evidence for out-of-equilibrium landscape features have for long been noticed in Bhutan, from major (> 1 km high) river knickpoints and from the existence of high-altitude low-relief surfaces within the mountain range. These geomorphologies were generally interpreted in the literature as representing a recent change in climatic and/or tectonic conditions, either related to the uplift of the Shillong Plateau (climate/tectonic change) or to the initiation of uplift over a blind ramp within the mountain range (tectonic change).</p><p>To further characterize these geomorphologies and discuss their origin and meaning in terms of regional tectonic or climatic evolution, we perform a detailed quantitative geomorphometric analysis using c plots and basin averaged aggressivity metrics, at various spatial scales, from large Himalayan rivers to local streams draining the low-relief surfaces. Our results first emphasize that the morphology of Bhutan does not result from a general wave of incision propagating upstream, as expected from most previous interpretations. Rather, we find that the river network is highly unstable and dynamic, in particular for the rivers draining the low-relief surfaces, hampering a proper quantification of tectonics from classical approaches based on denudation or incision rates. Finally, we discuss the origin and meaning of the observed dynamics, and from there draw some useful guidelines for future morpho-tectonic studies of active landscapes.</p>

Landscape Change in the Steppe of Algeria South-West Using Remote Sensing

2018 ◽  
Vol 18 (1) ◽  
pp. 41-52
Author(s):  
Tayeb Sitayeb ◽  
Ishak Belabbes
Keyword(s):  
Remote Sensing ◽  
Social Systems ◽  
Bare Soil ◽  
Climatic Conditions ◽  
Landscape Dynamics ◽  
Landsat 8 ◽  
Natural Ecosystems ◽  
Stipa Tenacissima ◽  
Steppe Species ◽  
Sparse Vegetation

Abstract Landscape dynamics is the result of interactions between social systems and the environment, these systems evolving significantly over time. climatic conditions and biophysical phenomena are the main factors of landscape dynamics. Also, currently man is responsible for most changes affecting natural ecosystems. The objective of this work is to study the dynamics of a typical landscape of western Algeria in time and space, and to map the distribution of vegetation groups constitute the vegetation cover of this ecosystem. as well as using a method of monitoring the state of a fragile ecosystem by remote sensing to understand the processes of changes in this area. The steppe constitutes a large arid area, with little relief, covered with low and sparse vegetation. it lies between the annual isohyets of 100 to 400 mm, subjected to a very old human exploitation with an activity of extensive breeding of sheep, goats, and camels. Landsat satellite data were used to mapping vegetation groups in the Mecheria Steppe at a scale of 1: 300,000. Then, a comparison was made between the two maps obtained by a classification of Landsat-8 sensor Operational Land Imager (OLI) acquired on March 18, 2014, and Landsat-5 sensor Thematic Mapper (TM) acquired on April 25, 1987. The results obtained show the main changes affecting the natural distribution of steppe species, a strong change in land occupied by the Stipa tenacissima steppe with 65% of change, this steppe is replaced by Thymelaea microphylla, Salsola vermiculata, lygeum spartum and Peganum harmala steppe. an absence from the steppe Artemisia herba-alba that has also been replaced by the same previous steppes species. The groups with Quercus ilex and Juniperus phoenicea are characterized by a strong regression that was lost 60% of its global surface and transformed by steppe to stipa tenacissima and bare soil.

scholarly journals MORPHOTECTONIC EVALUATION OF SIRCH MOUNTAINS USING WATER BASIN GEOMORPHIC INDICES

2021 ◽  
Vol 13 (2) ◽  
pp. 208-214
Author(s):  
Nafise HOSEINI ◽  
◽  
Shahram BAFTI ◽  
Reza DERAKHSHANI ◽  
Mohammad GHANBARIAN ◽  
...  
Keyword(s):  
Information System ◽  
Form Factor ◽  
Geographical Information System ◽  
Active Tectonics ◽  
Geographical Information ◽  
Tectonic Activity ◽  
Mountainous Region ◽  
Large Area ◽  
Active Tectonic ◽  
Morphotectonic Indices

Morphotectonic indices are useful instruments for investigating the effect of tectonic activity in a certain region. Calculation of these indicators using the advantages of Geographical Information System, GIS, in a large area is useful for detecting potential disorders related to active tectonics. This method is useful in regions on which few morphotectonic studies have been conducted. An example of such areas can be the watersheds of the Sirch mountainous region. The watersheds of the Sirch region located in Central Iran’s zone in the southeast of Iran are a very ideal zone to evaluate the concepts of these indicators in the prediction of the relative tectonic activity according to the investigation of drainage systems or mountain fronts. Based on the values of the calculated indices including Form Factor (FF), Compaction Coefficient (CC), Ratio of Circularity (RC), Ratio of Elongation (RE), relative Basin Height (BH), and Ruggedness Number (RN), a final indicator called Active Tectonic Indicator (ATI) is obtained. The latter is a combination of the abovementioned indicators and evaluates the morphotectonic activity based on the shape of the watersheds. By measuring and combining these indicators, the tectonic activity stage of the Sirch region was determined by analyzing the watersheds of this region.

scholarly journals Deep oceanic submarine fieldwork with undergraduate students, an exceptional immersive experience (Minerve software)

2021 ◽  
Author(s):  
Marianne Métois ◽  
Jean-Emmanuel Martelat ◽  
Jérémy Billant ◽  
Muriel Andreani ◽  
Javier Escartin ◽  
...  
Keyword(s):  
Undergraduate Students ◽  
Active Fault ◽  
Active Tectonics ◽  
Deep Ocean ◽  
Remotely Operated Vehicle ◽  
Promising Tool ◽  
Active Tectonic ◽  
Teachers And Students ◽  
High Resolution Models ◽  
To Come

Abstract. We present the content and scripting of an active tectonic lab-session conceived for third year undergraduate students studying Earth Sciences at Observatoire des Sciences de l’Univers of Lyon. This session is based on a research project conducted on the submarine Roseau active fault in Lesser Antilles. The fault morphology is particularly interesting to map as this structure in the deep ocean is preserved from weathering. Thus high resolution models computed from Remotely Operated Vehicle videos (ROV) provide exceptional educational material to link fault morphology and coseismic displacement. This5class, composed of mapping exercises on GIS and virtual fieldwork, aims at providing basic understanding of active tectonics,and in particular active fault morphology. The work has been conducted either in a full remote configuration via 3D online models or in virtual reality (VR) in a dedicated room using the Minerve software. During the VR sessions, students were either alone in the virtual environment or participated as a full group, including the teacher (physically in the classroom or remotely, from another location), which is to our knowledge one of the first attempts of this kind in France. We discuss on the efficiency10of virtual fieldwork using VR based on feedback from teachers and students, and we conclude that VR is a promising tool to learn observational skills, subject to certain improvements which should be possible in the years to come.

scholarly journals Multi-scale data on intertidal macrobenthic biodiversity and environmental features in three New Zealand harbours

2019 ◽  
Author(s):  
Casper Kraan ◽  
Barry L. Greenfield ◽  
Simon F. Thrush
Keyword(s):  
New Zealand ◽  
Environmental Variables ◽  
Spatial Organization ◽  
Spatial Scales ◽  
Species Distributions ◽  
Sediment Grain Size ◽  
High Resolution Data ◽  
Multi Scale ◽  
Grain Size Distributions ◽  
Patterns And Processes

Abstract. Understanding how the plants and animals that live in the seafloor vary in their spatial patterns of diversity and abundance is fundamental to gaining insight in the role of biodiversity in maintaining ecosystem functioning in coastal ecosystems, as well as advancing the modelling of species distributions under realistic assumptions. Yet, it is virtually unknown how the relationships between abundance patterns and different biotic and environmental processes change depending on spatial scales, which is mainly due to a lack of data. Within the project Spatial Organization of Species Distributions: Hierarchical and Scale-Dependent Patterns and Processes in Coastal Seascapes at the National Institute for Water and Atmospheric Research (NIWA) in New Zealand we collected multi-scale and high-resolution data on macrobenthic biodiversity. We found 146 species, i.e. bivalves, polychaetes and crustaceans (> 500 μm) that live hidden in marine sandflats, and collected point measurements of important environmental variables (sediment grain-size distributions, chlorophyll a concentration, and visible sandflat parameters) in three large intertidal Harbours (Kaipara, Tauranga and Manukau). In each Harbour we sampled 400 points for macrobenthic community composition and abundances, as well as the full set of environmental variables. Using an elaborate sampling design, we were able to cover scales from 30 centimetres to a maximal extent of 1 km. All data and extensive metadata are available from the data publisher PANGAEA via the persistent identifier https://doi.org/10.1594/PANGAEA.903448.

scholarly journals Spatial Relationship between Precipitation and Runoff in Africa

2018 ◽  
Author(s):  
Fidele Karamage ◽  
Yuanbo Liu ◽  
Xingwang Fan ◽  
Meta Francis Justine ◽  
Guiping Wu ◽  
...  
Keyword(s):  
Land Surface ◽  
Spatial Scales ◽  
Spatial Relationship ◽  
Resource Planning ◽  
Climatic Conditions ◽  
Runoff Coefficient ◽  
Global Precipitation Climatology Centre ◽  
High Runoff ◽  
Monthly Runoff

Abstract. Lack of sufficient and reliable hydrological information is a key hindrance to water resource planning and management in Africa. Hence, the objective of this research is to examine the relationship between precipitation and runoff at three spatial scales, including the whole continent, 25 major basins and 55 countries. For this purpose, the long-term monthly runoff coefficient (Rc) was estimated using the long-term monthly runoff data (R) calculated from the Global Runoff Data Centre (GRDC) streamflow records and Global Precipitation Climatology Centre (GPCC) precipitation datasets for the period of time spanning from 1901 to 2017. Subsequently, the observed Rc data were interpolated in order to estimate Rc over the ungauged basins under guidance of key runoff controlling factors, including the land-surface temperature (T), precipitation (P) and potential runoff coefficient (Co) inferred from the land use and land cover, slope and soil texture information. The results show that 16 % of the annual mean precipitation (672.52 mm) becomes runoff (105.72 mm), with a runoff coefficient of 0.16, and the remaining 84 % (566.80 mm) evapotranspirates over the continent during 1901–2017. Spatial analysis reveals that the precipitation–runoff relationship varies significantly among different basins and countries, mainly dependent on climatic conditions and its inter-annual variability. Generally, high runoff depths and runoff coefficients are observed over humid tropical basins and countries with high precipitation intensity compared to those located in subtropical and temperate drylands.

scholarly journals Geomorphological indicators of large-scale climatic changes in the Eastern Bolivian lowlands

2006 ◽  
Vol 61 (2) ◽  
pp. 120-134 ◽  
Author(s):  
J. May
Keyword(s):  
South America ◽  
Large Scale ◽  
Climate Changes ◽  
Landscape Evolution ◽  
Spatial Scales ◽  
Climatic Changes ◽  
Climatic Conditions ◽  
Fluvial Erosion ◽  
Paleoclimatic Significance ◽  
Bolivian Lowlands

Abstract. This study provides an inventory of geomorphological landforms in Eastern Bolivia at different spatial scales. Landforms and associated processes are interpreted and discussed regarding landscape evolution and paleoclimatic significance. Thereby, preliminary conclusions about past climate changes and the geomorphic evolution in Eastern Bolivia can be provided. Fluvial and aeolian processes are presently restricted to a few locations in the study area. A much more active landscape has been inferred from large-scale Channel shifts and extensive paleodune Systems. Mobilization. transport and deposition of Sediments are thought to be the result of climatic conditions drier than today. However. there are also indications of formerly wetter conditions such as fluvial erosion and paleolake basins. In conclusion, the documentation and interpretation of the manifold landforms has shown to contain a considerable amount of paleoecological information, which might serve as the base for further paleoclimatic research in the central part of tropical South America.

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